1. Field of Invention
The present invention relates to a new method for preparation of bis (2-dialkylaminoethyl) ether.
2. Description of Related Arts
Bis (2-dialkylaminoethyl) ether, is an important kind of organic chemical intermediate, which can be used as a catalyst for polyurethane foam synthesis. And the general chemical structure of it was shown in S-1.

According to -the related literatures, bis (2-dialkylaminoethyl) ether is prepared mainly by the following method currently:
1) Etherification reaction between N,N-dialkylchloroethylamine and N,N-dialkylethanolamine sodium salt is employed to obtain the target compound. The reaction temperature is above 100° C. and the reaction time is 6 hours, the product yield is around 60%. In this method, a lot of chloride sodium is produced as side product and the reaction environment is strongly corrosive.
2) The above method has been improved in literatures by using N,N-dialkylethanolamine sodium and N,N-dialkylethanolamine as the raw materials and chlorosulfonic acid, sulfoxide chloride and sulfonyl chloride were added as chloridizing agents in one pot. Long-chain alkane was used as solvent, and the reaction temperature is 50-100° C. The yield rate is around 50% after reacting about 3 hours. However, the defects of the original method still remain.
3) In patent U.S. Pat. No. 4,247,482 (1981), a method was reported by using N,N-dialkylethanolamine sodium salt as raw material and sulfur trioxide as catalyst. The reaction temperature is 110° C. and the reaction time is over 5 hours; the yield rate is around 61%. The main shortcoming of that method is that the way to feed sulfur trioxide is trivial and sulfur trioxide is not environmentally friendly.
4) In patent U.S. Pat. No. 4,474,988 (1984), a continuous reaction was reported by using N,N-dialkylethanolamine as raw material and solid alkaline zeolite as catalyst. The reaction temperature is 325° C. and the reaction time is 5 hours. The N,N-dialkylethanolamine conversion rate reaches over 90%. However, the selectivity of the target product is lower than 20%. The shortcomings of this method are high reaction temperature, poor selectiveness and low yield rate.
Therefore, there are still some defects in the currently available methods for preparation of bis (2-dialkylaminoethyl) ether, which are urgent to solve and improve.